Typically, in a light emitting module for backlighting or sidelighting a liquid crystal display, a light emitting device is mounted on a circuit board, and the light emitted from the light emitting device is dispersed and emitted at a wide angle via a lens. Using such a lens, a wide area may be uniformly illuminated with a small number of light emitting devices, by evenly dispersing the light emitted by the light emitting devices.
Recently, there has been a need to reduce the diameters of the lenses of light emitting modules due to the trend toward miniaturization, and flange parts have been formed on the light emitting surface in order to reduce the lens diameter.
However, in the prior art, luminance non-uniformity (mura) has occurred at the flange part when light diffused by the upwardly-sloping surface or flat surface formed on the back side (lower surface) of the lens is emitted toward the flange part, and as a result there has been a problem of non-uniform luminance.    Patent Reference 0001: Republic of Korea Unexamined Patent Publication 10-2015-0082394 (published 2015.07.15)